Telephone-exchange system.



A. E. LUNDELL.

TELEPHONE EXQHANGE SYSTEM. APPLICATION FILED SEPT. 1 h 1916.

Patented July 10, 1917.

NTE s AT FTQ.

ALBEN E. LUNDELL, OF NEW YORK, N. Y., ASSIGNOR TG WESTERN ELECTRIC COMPANY, INCORPORATED, 015 NEW YORK, N. Y., A OORPQRATION OF NEW YORK.

TELEPHONE-EXCHAN GE SYSTEM.

Specification of Letters Patent.

Patented July 1M), 1917.

To all whom it may concern:

Be it known that I, ALBEN E. LUNDELL, a. citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to improvements in telephone systems, and more particularly to the provision of means whereby a subscriber is prevented from disabling anothers line.

In certain automatic and semi-automatic telephone systems, difliculty is often eXpe rienced owing to the fact that when a connection is established between a calling and a called subscriber, which connection can only be released by the calling subscriber, the called subscribers telephone is rendered inoperative for making a call as long as this connection is maintained. Thus, a calling subscriber may either negligently or maliciously tie up another subscribers telephone by failing to hang up his receiver so as to release the connection which he has established.

In certain other systems, this difliculty has been overcome by having the connector arranged to return to normal as soon as the called subscribers telephone is replaced on its hook, so that the called subscriber is free at all times to use his line as he wishes. But such an arrangement does not permit the calling subscriber to resignal the called subscriber if the latter prematurely hangs up, and such resignaling is, often desirable.

It is the object of this invention to provide a circuit arrangement whereby a calling subscriber is prevented from tying up anothers line, but is still enabled to signal the called subscriber even after the latter has once responded and has replaced his receiver upon its hook.

The object of this invention is attained by so arranging the called partys circuit that he may restore the mechanism through which the connection was established by placing the receiver on the switchhook and subsequently removing it. While he is thus free at all times to clear his line and initiate a new call, yet if he merely replaces his receiver 011 the hook, his line is held in connection with the calling partys line until this calling party hangs up and thereby releases the connection.

In a preferred form of this invention, a relay controlled by the calling party, and a second relay controlled by the called party, have been provided. After the connection has been established and a signaling mechanism to summon the called party has been actuated under control of the first of these relays, a circuit is prepared by the signaling device incident to the response of the called party for bringing a slowacting relay under control of the second of these relays. At the termination of the conversation, the slow-acting relay prepares a second circuit for I putting a restoring means under the control of the second relay, so that should the called party now remove the receiver from its hook and thereby actuate the relay under his control, the restoring means will immediately act to free the line. If, on the other hand, the calling party should wish to recall the party with whom he had just been conversing, he may by quickly actuating his switchhook or by actuating his dial switch, so control the first-mentioned relay that the signaling device is again set in action, and the firstmentioned circuit and, in turn, the second mentioned circuit is destroyed.

The accompanying drawing represents diagramatically the circuits of a well-known connector switch and so much of the arrangements of a telephone exchange system as is necessary for a clear understanding of the present invention.

Suppose that a calling subscribers station A has been extended by well-known manual or automatic means to a trunk represented here by the conductors l and 2. It will be seen that a circuit is established from grounded battery, through the right-hand winding. of the line relay 3, conductor 2, substation of calling subscriber A, conductor 1, left-hand winding of line relay 3, and thence to ground. Relay 3 becomes energized and closes a circuit for slow-release relay 4 from grounded battery, winding of relay 4:, alternate contact and armature of relay 3, and thence to ground. The subscriber now proceeds to send out, through forth between its alternate and normal contacts in accordance with the numerical designation of the called line.

Relay 1 being slow to release does not become deenergized upon the interruptions produced in its circuit by the vibration of the armature of relay 3, and therefore, upon each release of said armature, a circuit is establishedfrom grounded battery through the winding of the primary magnet 8, contact and wiper 10 in position 1 of aside switch associated with connector switch S, alternate contact andarmature of relay l, normal contact and armature of relay 3 to ground; Under the control of magnet 8, wipers 11, 12 and 13 ofthe connector switch S are stepped in a rotary direction. 7

Upon the first release of the armature oi relay 3, a circuit wasclosed for relay 14 from grounded battery, through the winding of relay 1a, alternate contact and armature of relay 4, normal contact and armature of relay 3 to ground, and thereafter relay 14 beingquick to act and slow to release in the same manner as relay 1, remains energized during the vibrations of the armature of relay 3. Relay 14 closes a circuit from grounded battery through the winding of escapement magnet 16, contact and wiper 15in the first position of the side switch, contact and armature of relay 14: to ground. Relay '16 controls upon its deenergization the stepping of the side-switch wipers, so that after thecalling subscriber sends out the first series of impulses and the circuit of line relay 3 is uninterrupted at the call- 7 ing substation for a sufiiciently long period to allow the deenergization of slow-release relay 14%, its armatures resume their normal position. Magnet 16 is thereupon deenergized and the wipers of the side switch move into the second position.

'The calling subscriber proceeds now to send out the second set of directive impulses, stepping the connector switch wipers in a vertical direction under the control of a secondary magnet 9. After the second series ofi'mpulses have been sent out, line relay 3 remains energized and opens at its normal contact the circuit of slow-release relay .14. If the called subscribers' line is idle, the test wiper 13 of connector switch S does not find ground on the test conductor, and therefore escapement magnet 16 becomes deenergized upon the opening of its circuit by slow-release relay 14, and

moves the side-switch wipers into position 3.

In position 3, the'subscribers line B is connected to the trunk represented by conductors 27 and 28, through the side-switch wipers 17 and 18, and this subscribefls bell is rung in the following manner: Armature of line relay 3 having established a connection with its alternate contact, by so doing has closed an energizing circuit for relay 6 from grounded battery, ringing relay 6, right-hand armature and normal contact of relay 5, arnniture and contact of relay 7, armature and alternate contact of line relay 3, to ground. Relay 6 which has therefore been energized before the side-switch wipers 17, 1S and 19 have moved into position 3, now completes a circuit from the source oi ringing current 20 through the winding of trip ping relay 7, lowe' armature and alternate contact of relay 6 through the called subscribers line and bell, uppe' armature and alternate contact of relay 6 to ground. Tripping relay 7 is known as a marginal relay since it is so adjusted that the current traveling through it to ring the bell of the subscribers line is not sufficient to *ause it to operate, while the current traveling through it after the subscriber has removed his receiver from the hook is sufhcient to cause it to operate. The movement of the armature of relay 7, when the called subscriber. in answer to the summons of his bell, does remove the receiver from the switchhook, interposes relay 5 in the circuit traced. for relay (3. Relay 5 thereupon operates and in so doing sets up a locking circuit for itself and shunts relay (3. The circuit for relay 5 now may be traced from grounded battery, right-hand armature and alternate contact of relay 5, winding of relay 5, alternate contact and armature of relay 3 to ground. Since both sides of the winding of relay 6 are now connected to grounded battery, current ceases to flow through this relay and its armatures resume their normal position.

Line relay 21 is now out into circuit to supply talking current to the substation B, and its armature moves up to make connection with its alternate contact.

Suppose the subscriber B hangs up prematurely. By working his hook switch quickly, subscriber A may produce one or more impulses of short duration in the line so that the armature of relay 3 will vibrate in a manner similar to that when the directive impulses are being sent out. The circuit for relay 5, heretofore traced, is therefore opened for a very short space of time at the alternate contact and armature of relay 3. The armatures of relay 5 thereupon resume their normal position, and since the armature of relay 7 is in its normal position, relay 5 becomes short-circuited and relay 6 is again energized over the circuit previously traced. In this manner the subscriber B is resignaled.

If, on the other hand, the subscriber B removes his receiver from the hook. before subscriber A has hung up or before subscriber A. has actuated his receiver hook to resignal subscriber B, the armature of line relay 21 will travel forward to make connection with its alternate contact. When, previously, the armatures of relay 5 had moved into their alternate position, and thereby deenergized relay 6, which in turn caused line relay 21 to be cut into circuit, a circuit was momentarily established for relay 22 from grounded battery, left-hand armature and contact of relay 5, the winding of relay 22, normal contact and armature of line relay 21 to ground. Relay 22, how ever, is a slow-acting relay, and hence, before its left-hand armature could move up and establish a locking circuit, this circuit was broken by the movement of the armature of line relay 21, and the armature of relay 22 failed to make connection with their contacts. When the subscriber B had hung up, this circuit was again established and a holding circuit was provided for relay 22 from grounded battery, left-hand armature and contact of relay 5, relay 22, lefthand armature and contact to ground.

Now, when the armature of relay 21 moves again to make connection with its alternate contact, in response to the current flowing through its windings caused by the removal of the receiver from its hook at substation B, a circuit is set up from grounded battery, through the winding of release magnet 23, the oft-normal contact 24, right-hand armature and contact of relay 22, alternate contact and armature of relay 21 to ground. Release magnet 23, in energizing, closes a holding circuit for itself from grounded battery, winding of relay 23, off-normal contact 24, contact and armature of relay 23 to ground. The apparatus connected with substation B is thereupon released and subscriber B is free to use his line as he wishes.

Relays 25 and 26 represent the well-known means through which the line finder and selector switches are released when the subscriber at station A hangs up.

What is claimed is:

1. In a telephone system, a calling subscribers line and a called subscribers line, means including an automatic switching device for interconnecting said lines, a source of ringing current, means for applying said ringing current to said called subscribcrsline, restoring means for said switching device controllable over either of said lines, and means for reapplying said ringing current to said called subscribers line.

2. In a telephone system, a calling subscribers line and a called subscribers line, means including an automatic switching device for interconnecting said lines, a source of ringing current, a relay, means controlled by said relay to automatically apply .said ringing current to said called subscribers line, restoring means for said switching device, means operated over the called subscribers line to actuate said restoring means, and means for reapplying said ringing current to said called subscribers line.

3.. In a telephone system, a calling subscribers line and a called subscribers line, substations in which said lines terminate, means including an automatic switching device for interconnecting said lines, a source of ringing current, a relay, means including said relay to apply said ringing current 'to said called subscribers line a desired number of times under the control of said calling subscriber, restoring means for said switching device, and means jointly controlled by the called substation and said relay to actuate said restoring means.

4. InIa telephone system, a calling sub scribers line and a called subscribers line, substations in which said lines terminate, means including an automatic switching device for interconnecting said lines, a source of ringing current, a relay, means including said relay to apply said ringing current to said called subscribers line a desired number of times under the control of said calling substation, restoring means for said switching device, a second relay controlled in part by said first relay, and means in cluding said second relay and controlled from the called substation to operate said restoring means.

5. In a telephone system, a calling subscribers line and a called subscribers line, substations in which said lines terminate, means including an automatic switching device for interconnecting said lines, rest-oring means for said switching device, a re lay, means including said relay for signaling and resignaling the called substation, a circuit for said restoring means controlled from the called substation, a slowacting relay controlled by said first relay, and means including said slow-acting relay for preparing said circuit.

6. In a telephone system, a calling subscribers line and a called subscribers line, substations in which said lines terminate, means including an automatic switching device for interconnecting said lines, restoring means for said switching device, an operating circuit for the same, a relay, means including said relay for signaling and resignaling the called substation, a slow-acting relay, and an operating circuit for said slowacting relay controlled in part by said first relay, said slow-acting relay controlling the operating circuit for said restoring means.

7. In a telephone system, a calling subscribers line and a called subscribers line, means including an automatic switching dethe release of said switching device, circuit for said electromagnet controlled by vice for interconnecting said lines, a source of signaling current at said switching device, a relay for controlling the connection of said source of current to a called line, means for operating said relay upon the response of a called subscriber to cause said source of current to be disconnected troin said line, an electromagnet for controlling and a said relay. 7

8. In a telephone system, a calling subscribers line and a called subscribers line, means including an automatic switch for establishing a connection from one of said lines to the other, a source of ringing current at said switch, means for connecting said source oit current to a called subscribers line, a relay, means for causing the operation of said relay upon the response of a called subscriber to remove said ringing current from said line, means under the control' of the callingsubscriber for operating said relay toagain connect said source of current to thecalled line, an electromagnet for controlling the release of said switch, and a circuit for said electromagnet controlled by said relay.

9. In a telephone exchange system, a calling subscribers line and a called subscribers line, means including an automatic switch for establishing a connection between said lines, a release magnet for said'switch, a

' relay for controlling the circuit of said re- V lease magnet, means including a relay for energizing said first-mentioned relay upon the opening of the called subscribers line, said second-mentioned relay operating upon a subsequent closure of the called subscribers line, and a circuit for said release magnet extending through contacts of said ringing current calling s'ubscribers relays. v p

10. In a telephone exchange system, a calling subscribers line and a called subscribers line, means including an automatic switch for establishinga connection from one of said lines to the other, a source of ringingcurrent, means for connecting said source of current to the called line, a relay, means for operating said relay upon the response of the called subscriber to cause the removal of ringing current from said line, a locking circuit for said relay, a relay under the control of the calling subscriber for breaking said locking circuit to cause said to be again applied to the called line, an electromagnet for controlling the release of said switch, and a circuit controlled by said first-mentioned relay for controlling said electromagnet.

11. In a telephone exchange system, a

line and a called subscribers line, means including an automatic switch for establishing a connection from one of said lines to the other, a source of ringing current, means for automatically connecting said source of current to the called line upon completion of a connection, a relay, means for operating said relay upon the response of the called subscriber to cause the removal of ringing current from the called line, a magnet for controlling the release of said switch, a relay controllable over the called subscribers line, and a circuit for said magnet controlled jointly by said relays.

12. In a telephone system, a calling subscribers line and a called subscribers line, means including an automatic switch for completing a connection from one of said lines to the other, a source of ringing current, means for connecting said source of current to the called subscribers line, a relay, means for operating said relay upon response of the called subscriber to cause the removal of said current from said line, a locking circuit "for said relay, means under the control of the calling subscriber tor iiiterrupting said locking circuit to again join said source of current to the called line, a release magnet for said switch. a slowacting relay, a line relay controllable over the called subscribers line, a circuit for said slow-acting relay extending through contacts of said first-mentioned relay and said line relay, said line relay operating upon the opening of the circuit of the called subscribers line to complete the circuit of said slow relay, and a circuit for said release magnet extending through contacts of said slow relay and contacts of said line relay, said last-mentioned circuit being, closed upon a. subsequent reverse operation of said line relay.

1 8. In a telephone system, a calling subscribers line and a called subscribers line, means including an automatic switch for completing a connection between said lines, a release magnet for said switch, a line relay controllable over the called subscribers line, a slow-acting relay, a circuit for said slowacting relay extending through the contacts of said line relay, a locking circuit for said slow-acting relay, said first-mentioned circuit being closed upon the opening of the circuit of the called subscribers line, said locking circuit thereafter holding said slowacting relay energized, a circuit for said release magnet extending through the contacts of said slow-acting relay and said line relay, said last-mentioned circuit being closed upon a subsequent closure of the circuit of the called subscribers line.

14. In a telephone system, a calling subscribers line and a called subscribers line, means including an automatic switching device for interconnecting said lines, a source of ringing current, means for automatically applying said ringing current to said called subseribers line, means for disconnecting said source of ringing current from said called subscribers line incident to the response of said called subscribers line, restoring means for said switching device controllable over said called subscribers line,

Copies of this patent may be obtained for five cents each, by addressing the and means for reapplying said ringing current to said called subscrlbers line.

In Witness whereof, I hereunto subscribe 131 my name this 8th day of September A. D., 1916.

ALBEN E. LUNDELL.

Commissioner of Patents,

Washington, D. G. 

